Tracking something means keeping in mind, as a live variable. Examples:

• "Are you tracking that he's not in the right mood for complicated ideas right now?"
• "A hypothesis I'm tracking is that I might be dehydrated, but if we sit in the shade and feel better I'm probably just hot."
• "I'm tracking that there might be an opportunity to use wadgets to complete this much faster."
• "I'm not tracking the social consensus at that company because I don't know people there and they don't post publicly."

Tracking is very roughly synonymous with "keeping track of". But there are some subtleties:

• They both imply keeping up to date about something.
• Tracking also implies keeping something in mind, beyond just updating about it. You might also put the knowledge into action. For example, someone might ask "Are you tracking that we have to leave in 3 minutes?", meaning "Are you set up so that you'll coordinate your actions in the next couple minutes, to be ready to go?".
• "Keeping track of" X sounds like X is fairly concrete or straightforward to understand, like you could write down a number that registers a sufficient summary of X. "Tracking" X could mean "holding in awareness in order to update, but without expecting a specific predefined kind of update". For example, you could say "I'm tracking my confusion about what goals even are.". This doesn't just mean "I'm keeping track of the fact that I'm confused about goals."; it also means "I'll avoid putting too much weight on my concept of goals, for now." and "I'll seize good opportunities to clarify my concept of goals.".

Tracking is more demanding, and a higher bar. If you're tracking X, it means you're affording X a significant spot in your thinking, e.g. it takes up some of your attention or working memory.